CIVIL LOGS

FLY-ASH INTRODUCTION. Fly ash brick First invented in 2007..... American civil engineer Henry liu announced the invention of a new type of fly ash brick in 2007. Lius’s brick is compressed of at 4,ooo psi and cured for 24 hrs in a 150 F(66 C) steam bath, then toughened with air entrainment agent , so that it lasts for more than 100 freeze thaw cycles. Owing to high concentration of calcium in class c fly ash , the brick can be described as self cementing. Since method contains no clay and uses pressure instead of heat ,it saves energy, reduces mercury pollution,costs 20% less than traditional manufacturing techniques.  This type of brick is now manufactured under license in USA.  Fly ash bricks are constructed at least partially from the residue of burnt coal .Depending on the type of coal that is burned, the resulting fly ash can take a number of different forms. Some kinds of fly ash require a cementing agent, such as quicklime or Portland cement . Other types contain a larg...

1                                                             ABSTRACT This study presents the investigations of effect of fly-ash on concrete containing slag. Cement is a costly material and is used extensively for construction works all over the world. Replacing a certain fraction of cement by fly-ash contributes to the strength of concrete due to its pozzolanic reactivity. However, since pozzolanic reaction is slow, the initial strength is low.  fig-1. This pozzolanic reaction also makes the structure of concrete denser, resulting in decrease in water and gas permeability. Slag is generated during iron and steel production. The addition of slag reduces the rate of heat evolution and increases the resistance to chemical attack. It is made use of in hot regions due to less effect on early strength of concrete. The percentage of ...